Dean Moltrer laughs at finding mail in a Segundo mailbox crushed when the 5.3-magnitude earthquake collapsed the front of a brick building in the southern Colorado town. The quake was the state's strongest since a magnitude 5.3 in August 1967.

Steve Newman jumps with students as he talks to his seventh-grade science class Tuesday aboutthe seismograph under his classroom floor at Kent Denver School. Research on the quake nearTrinidad gave students a close-to-home look at earth science.

An unusual swarm of temblors in southern Colorado accompanied the state’s strongest earthquake in more than 40 years, shaking bricks and stones loose from buildings and rattling some residents.

“The whole house shook, the bookshelves, the paintings,” said Melissa Mestas, a barista at the What’a Grind Coffee House in Trinidad. “It was really scary and just this helpless feeling.”

The 5.3-magnitude earthquake hit Monday shortly before midnight about 9 miles southwest of Trinidad. Throughout the night and into Tuesday morning, aftershocks — several measuring at a magnitude of 3 or above — continued to unsettle residents. No injuries were reported.

Tuesday morning, the conversation at the coffee house centered on where everybody was when the earthquake hit, Mestas said. Along with the coffee house, several older historical buildings in Trinidad’s downtown had minor damage.

The longtime resident said she is familiar with smaller earthquakes but has never been through one as powerful as Monday night’s.

“It’s piqued a lot of curiosity as to what’s caused this,” Mestas said.

Rare, not unheard of

While strong earthquakes and swarms of aftershocks are rare in Colorado, they do have a history in the area, said Gavin Hayes, a seismologist at the U.S. Geological Survey’s National Earthquake Information Center in Golden.

Southern Colorado sits over a fault in the tectonic plate, Hayes said. Over time, stress builds as the two sides of the fault rub together. The stress is eventually released in a strong earthquake and followed by several smaller earthquakes known as an earthquake swarm.

Earthquake swarms are rare in Colorado, compared with other states, such as California, that sit on the edge of a tectonic plate.

“At the moment, it just seems like the quake is consistent with the region and the historic activity in the area,” Hayes said.

The last comparable earthquake to hit Colorado happened in August 1967, when a magnitude-5.3 earthquake hit in the same area.

Las Animas County Sheriff Jim Casias said Tuesday afternoon that authorities and engineers were completing safety checks on buildings and roads.

The earthquake caused rock slides on Colorado 12 and several county roads. Authorities are worried that heavy rains could cause the loose rocks to wash out without warning, Casias said.

Older homes and buildings in the area are particularly susceptible to damage as aftershocks continue.

“Everybody’s just frazzled,” Casias said. “It’s got a pretty big impact on you and your families.”

Ringo’s Super Trading Post in Segundo was closed Tuesday after the earthquake shook groceries off shelves and damaged several antiques, said manager Theresa James.

“It’s a lot of cracks right now,” James said. “The building is still sound, but it has shifted, no doubt.”

Segundo is less than 5 miles from the epicenter of the earthquake.

While Colorado’s quake is similar to one that occurred Tuesday afternoon in Virginia, there is nothing to indicate they were connected, Hayes said.

Students in Steve Newman’s seventh-grade science class got a chance at a first-hand look at both earthquakes during their first day of school Tuesday. A student-built seismograph, nestled in a crawl space underneath a classroom at Kent Denver School in Englewood, captured the earthquakes and provided students with this year’s first homework assignment — researching the Trinidad earthquake.

“The classroom is plastered with readings from the earthquakes in Haiti and Japan,” Newman said. “This will be an impressive introduction to earth science and how it can strike near home.”

Jordan Steffen was the legal affairs reporter for The Denver Post. She left the organization in June 2016 after joining in January 2011. Her past coverage areas included breaking news, child welfare, the western suburbs and crime. She was raised in the Colorado mountains and graduated from the University of Colorado Boulder.

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